Saturday, November 26, 2011

A quick note regarding the hardware

After receiving a few questions about eLuaBrain, it is clear that I need to clarify something: eLuaBrain is just a prototype at the moment, it does not NEED a STM321E-EVAL board in order to function. A number of people wrote to me, complaining about the high price of the STM3210E-EVAL board (which is absolutely true). But the reality is that I used this board only because I already had it around and it has all the peripherals I needed (actually it has too many, I had to remove some resistors/capacitors to free some GPIO lines), plus a couple of very convenient header connectors for all the MCU pins. eLuaBrain needs only a small subset of the hardware on the STM3210E-EVAL:

- the MCU
- the external SRAM
- the serial port
- the SD/MMC card connector
- the 3.3V voltage regulator

(I hope I'm not forgetting something).
eLuaBrain is not even restricted to a particular MCU or even a MCU family. While some of its code is specific to the STM32F103 MCU, porting it to another STM32 MCU or another Cortex-M3/M4 core from other manufacturers (like NXP or TI) or even another architecture altogether shouldn't be too difficult (although my personal preference is a Cortex-M3/M4 core). Actually, using a MCU that has an integrated Ethernet subsystem would make more sense, as it would reduce the overall system cost and power consumption. There are a lot of possibilities here. As always, I'm curious about your oppinion. What would be your MCU of choice for eLuaBrain?


  1. Salut Bogdan!

    What about Chipkit Max32 board, available also in Romania from several online shops?

    I saw recently a discussion on eLua mailing list about Microchip C development tools. Here, is a topic started by Jason Kajita from Microchip and is about a completely open-source C compiler for PIC32 based on gnu gcc and Newlib library (in the topic you can find a link to download the compiler) which produce code highly optimized and without limitation on size.

    That compiler toolkit is used in compiling retroBSD (a UNIX variant) for Chipkit Max32 board.

    Best regards,
    Guta Ciucur Vasile

  2. Salut Ciucur!

    PIC32 was discussed a number of times on the eLua mailing list and there are some issues with it. From what I understood they aren't related only to the toolchain, but also to the chip support libraries which are released under restrictive licensing conditions. I guess this is one of the reasons we don't have an official eLua PIC32 port yet. eLuaBrain could probably run fine on PIC32; however, this is not really my MCU of choice, so I won't invest much effort in this area unless I find a very good reason to do so. Thank you for your suggestion.

  3. Hi Bogdan,

    what do you think of the possibility of bringing eluabrain on Mizar32?
    It should have already all the necessary hardware,
    in addition, the project meets some of my needs, take a computer to manage home automation.
    What do you think?

    1. Hi Nuccio,

      That is definitely doable. The port would require some effort, of course, but it can be done and I'm very curious about the end result.

  4. So hey, I think this project is one of the coolest I have ever seen in my ENTIRE life! I would like to contribute to expanding this project. I have experience with STM32 processors, and have several friends that have experience with other 32 bit MCUs. How can I find the schematics and source to start working on expanding this system? I have all the hardware necessary from what I gather from your current descriptions.

    1. Thanks for the kind words. All you need to build your own version of the brain should be in the documentation ( I'm also considering ports to various other (cheaper) platforms, please let me know if you are interested.